Tough choices, can't watch the video right now due to being on a trip so I will +1 to someone who wrote postponing the video for an unbiased opinion 
I would go to Keep the Mamiya Six for compactness, together with switching/upgrading the same camera model. I read there was red window advance but perhaps a latter series model should have automatic film advance. My 6x6 is a Super Ikonta IV, which has a coupled RF, Tessar lens and automatic film advance as well as being light and compact. My main camera is a Fuji 6x9.
The Mamiyas are fantastic cameras but are very expensive nowadays. GF670 would be also a great choice in that line; if afforded.
There is something special with Medium format and the "period correct" match of a classic 6x6 with the "frozen in time" Caribbean nation.

I would go to Keep the Mamiya Six for compactness, together with switching/upgrading the same camera model. I read there was red window advance but perhaps a latter series model should have automatic film advance. My 6x6 is a Super Ikonta IV, which has a coupled RF, Tessar lens and automatic film advance as well as being light and compact. My main camera is a Fuji 6x9.
It's an interesting point as the first (scan) results I had from the Super Ikonta's Tessar were a bit disappointing, but that was coming from the modern Fujinon of a much newer camera. Later on I came to terms with it stopping down and 10" wide prints look great.Nope. This is a 3x2" picture. There's no challenging light in it. A 35mm P&S could have been used to make that. You're conflating the artistic merits (that are excellent) with technical limitations of equipment (which is not stressed here at all). Or maybe you're just bragging. The photo is superb, I would have done the same![]()
But how many Cameras and film does the ongoing price for the M6 cover? OP can buy maybe 3 more of the current cameras, and have 6 for the Mamiya (pun).A new Mamiya 6 or 7 with 2 lenses would fit in a smaller bag ...... since you're measuring...
The Mamiyas are fantastic cameras but are very expensive nowadays. GF670 would be also a great choice in that line; if afforded.
Or exactly getting used to fixed focal lengths. I came to terms with it when in Medium format and even film in general.How many people in this thread find the need to change focal lengths when shooting 6x6? I got a Hasselblad ages ago thinking this would be a great draw. But I never took the 80 off the camera.
But I bet quite some interesting pictures to take in Havana, Cuba!Seems like this jumbo jet is landing in Cuba instead of Miami.
Just a little bit highjacked.
There is something special with Medium format and the "period correct" match of a classic 6x6 with the "frozen in time" Caribbean nation.